Question

Biology Tutorial: Introduction to Immunology

Answer 1

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Answer 2

\({\bf{Basic~Terminology:}}\)
- immunology: study of the immune system
- immunity: the ability to recognize and respond to pathogens
- antigen: a foreign substance that induces an immune response
- antibody: a blood protein that recognizes and combats the effects of an antigen

\({\bf{Types~of~Immunity:}}\)
Innate:
- not antigen specific
- consists of barriers, physical and chemical defenses, blood proteins, and specialized cells

Adaptive:
- antigen specific
- consists of blood proteins and specialized cells like B-cells and T-cells (more later)
- ex: skin, mucous, cilia, enzymes (which break down cell walls), maintenance of low pH (hostile to pathogens)

Answer 3

\({\bf{Immunity~by~System:}}\)

Skin:
- dendritic cells in epidermis recognize pathogens and induce T-cell response
- low pH
- local microbial population to compete with invading one
- antimicrobial secretions

Respiratory:
- mucous membranes
- secretions which trap/kill/otherwise inhibit microbes
- nasal hairs trap microbes before they can enter the body
- cilia moves pathogens to the pharynx for transport to digestive system
- phagocytosis through alveoli

Digestive:
- peristaltic motions transport pathogens down the tract
- expulsion of pathogens through waste
- low pH
- local microbial populations

Urinary:
- low pH of urine
- expulsion/washing out of pathogens through urine
- low pH due to glycogen breakdown

Ocular:
- blinking
- tears (enzymatic activity)

Answer 4

\({\bf{Defensins:}}\)
- host peptides that combat pathogens
- four families, alpha [neutrophils, paneth], beta [epithelial], insect, plant
- bind to the outer membranes/walls of bacteria, fungi, and yeast

\({\bf{Complement~System:}}\)
- three types: classical, alternative, lectin/MBL
- C3 molecules (complement component 3): required to activate the immune system
- induces the formation of the membrane attack complex (MAC) which induces cell lysis through pores

\({\bf{PAMPs:}}\)
- pathogen-associated molecular patterns
- highly conserved
- recognized by the immune system pathogen recognition molecules/receptors (PRM/PRRs)
- ex: bacterial cell wall components (so LPS, lipotechoic acids, peptidoglycan, etc. there's another tutorial on bacterial cell membranes if you're interested)
- ex: viral nucleic acids, glycoproteins

Answer 5

\({\bf{Adaptive~Immunity~in~Detail:}}\)
- specific
- immunological memory: after exposure to an antigen, clonal production results in a large body of antibodies, which causes a faster response when that same antigen is encountered

- B-cells: a white blood cell that presents antigen and secretes cytokines, forms and matures in (b)one marrow
> subtypes, memory B and plasma cells
> occupy the lymphatic system
> recognize antigens and divide (clonal expansion)

- T-cells: a white blood cell that posseses T-cell receptors; forms in bone marrow and matures in (t)hymus
> subtypes: memory, helper, suppressor, and killer
> primary function is to recognize/respond to antigens
> will only bind antigens with receptor molecules MHCI or MHCII

Answer 6

Anyway that's the end, I hope this is a useful resource. I am not an expert by any means but I will attempt to answer questions to the best of my ability.